1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "base/process/internal_linux.h"
6
7#include <limits.h>
8#include <unistd.h>
9
10#include <map>
11#include <string>
12#include <vector>
13
14#include "base/files/file_util.h"
15#include "base/logging.h"
16#include "base/strings/string_number_conversions.h"
17#include "base/strings/string_split.h"
18#include "base/strings/string_util.h"
19#include "base/threading/thread_restrictions.h"
20#include "base/time/time.h"
21
22namespace base {
23namespace internal {
24
25const char kProcDir[] = "/proc";
26
27const char kStatFile[] = "stat";
28
29FilePath GetProcPidDir(pid_t pid) {
30  return FilePath(kProcDir).Append(IntToString(pid));
31}
32
33pid_t ProcDirSlotToPid(const char* d_name) {
34  int i;
35  for (i = 0; i < NAME_MAX && d_name[i]; ++i) {
36    if (!IsAsciiDigit(d_name[i])) {
37      return 0;
38    }
39  }
40  if (i == NAME_MAX)
41    return 0;
42
43  // Read the process's command line.
44  pid_t pid;
45  std::string pid_string(d_name);
46  if (!StringToInt(pid_string, &pid)) {
47    NOTREACHED();
48    return 0;
49  }
50  return pid;
51}
52
53bool ReadProcFile(const FilePath& file, std::string* buffer) {
54  buffer->clear();
55  // Synchronously reading files in /proc is safe.
56  ThreadRestrictions::ScopedAllowIO allow_io;
57
58  if (!ReadFileToString(file, buffer)) {
59    DLOG(WARNING) << "Failed to read " << file.MaybeAsASCII();
60    return false;
61  }
62  return !buffer->empty();
63}
64
65bool ReadProcStats(pid_t pid, std::string* buffer) {
66  FilePath stat_file = internal::GetProcPidDir(pid).Append(kStatFile);
67  return ReadProcFile(stat_file, buffer);
68}
69
70bool ParseProcStats(const std::string& stats_data,
71                    std::vector<std::string>* proc_stats) {
72  // |stats_data| may be empty if the process disappeared somehow.
73  // e.g. http://crbug.com/145811
74  if (stats_data.empty())
75    return false;
76
77  // The stat file is formatted as:
78  // pid (process name) data1 data2 .... dataN
79  // Look for the closing paren by scanning backwards, to avoid being fooled by
80  // processes with ')' in the name.
81  size_t open_parens_idx = stats_data.find(" (");
82  size_t close_parens_idx = stats_data.rfind(") ");
83  if (open_parens_idx == std::string::npos ||
84      close_parens_idx == std::string::npos ||
85      open_parens_idx > close_parens_idx) {
86    DLOG(WARNING) << "Failed to find matched parens in '" << stats_data << "'";
87    NOTREACHED();
88    return false;
89  }
90  open_parens_idx++;
91
92  proc_stats->clear();
93  // PID.
94  proc_stats->push_back(stats_data.substr(0, open_parens_idx));
95  // Process name without parentheses.
96  proc_stats->push_back(
97      stats_data.substr(open_parens_idx + 1,
98                        close_parens_idx - (open_parens_idx + 1)));
99
100  // Split the rest.
101  std::vector<std::string> other_stats = SplitString(
102      stats_data.substr(close_parens_idx + 2), " ",
103      base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
104  for (size_t i = 0; i < other_stats.size(); ++i)
105    proc_stats->push_back(other_stats[i]);
106  return true;
107}
108
109typedef std::map<std::string, std::string> ProcStatMap;
110void ParseProcStat(const std::string& contents, ProcStatMap* output) {
111  StringPairs key_value_pairs;
112  SplitStringIntoKeyValuePairs(contents, ' ', '\n', &key_value_pairs);
113  for (size_t i = 0; i < key_value_pairs.size(); ++i) {
114    output->insert(key_value_pairs[i]);
115  }
116}
117
118int64_t GetProcStatsFieldAsInt64(const std::vector<std::string>& proc_stats,
119                                 ProcStatsFields field_num) {
120  DCHECK_GE(field_num, VM_PPID);
121  CHECK_LT(static_cast<size_t>(field_num), proc_stats.size());
122
123  int64_t value;
124  return StringToInt64(proc_stats[field_num], &value) ? value : 0;
125}
126
127size_t GetProcStatsFieldAsSizeT(const std::vector<std::string>& proc_stats,
128                                ProcStatsFields field_num) {
129  DCHECK_GE(field_num, VM_PPID);
130  CHECK_LT(static_cast<size_t>(field_num), proc_stats.size());
131
132  size_t value;
133  return StringToSizeT(proc_stats[field_num], &value) ? value : 0;
134}
135
136int64_t ReadProcStatsAndGetFieldAsInt64(pid_t pid, ProcStatsFields field_num) {
137  std::string stats_data;
138  if (!ReadProcStats(pid, &stats_data))
139    return 0;
140  std::vector<std::string> proc_stats;
141  if (!ParseProcStats(stats_data, &proc_stats))
142    return 0;
143  return GetProcStatsFieldAsInt64(proc_stats, field_num);
144}
145
146size_t ReadProcStatsAndGetFieldAsSizeT(pid_t pid,
147                                       ProcStatsFields field_num) {
148  std::string stats_data;
149  if (!ReadProcStats(pid, &stats_data))
150    return 0;
151  std::vector<std::string> proc_stats;
152  if (!ParseProcStats(stats_data, &proc_stats))
153    return 0;
154  return GetProcStatsFieldAsSizeT(proc_stats, field_num);
155}
156
157Time GetBootTime() {
158  FilePath path("/proc/stat");
159  std::string contents;
160  if (!ReadProcFile(path, &contents))
161    return Time();
162  ProcStatMap proc_stat;
163  ParseProcStat(contents, &proc_stat);
164  ProcStatMap::const_iterator btime_it = proc_stat.find("btime");
165  if (btime_it == proc_stat.end())
166    return Time();
167  int btime;
168  if (!StringToInt(btime_it->second, &btime))
169    return Time();
170  return Time::FromTimeT(btime);
171}
172
173TimeDelta ClockTicksToTimeDelta(int clock_ticks) {
174  // This queries the /proc-specific scaling factor which is
175  // conceptually the system hertz.  To dump this value on another
176  // system, try
177  //   od -t dL /proc/self/auxv
178  // and look for the number after 17 in the output; mine is
179  //   0000040          17         100           3   134512692
180  // which means the answer is 100.
181  // It may be the case that this value is always 100.
182  static const int kHertz = sysconf(_SC_CLK_TCK);
183
184  return TimeDelta::FromMicroseconds(
185      Time::kMicrosecondsPerSecond * clock_ticks / kHertz);
186}
187
188}  // namespace internal
189}  // namespace base
190